Electron-discharge device



ELEGTHON DI SCHARGE DEVI CE Filed July 30. 1924 Patentes Aug. e, i927.

` Unirse stares iaasisi earner' eiseres.

VICTOR L. RONCI, OF BROOKLYN, NEW YORK, ASSIGNOB T WESTERN ELECTRIC COM- PANY, INCORPORATED, OF ANEW YORK, N..Y., A COBBOBATION 0F NEW YORK.

macminer-Discman nevica.

application mea my 3o, i924. semi no. 729,016.

This invention relates to electron discharge devices and pertains more especially to the evacuation of such devices. l

In devices of this character it is prefer- 8 able to complete the evacuation of the vessel by vaporizing a reducing medium or getter, such as calcium or magnesium', to absorb the remaining gas. This process consists of flashing or otherwise heating the relu ducing medium to the vaporization point whereby the vapor absorbs the gases and deposits in the form of a silvery coating or film on the interior wall of the Vessel. Due to the spreading of the vapor of the reducing medium over the entirev wall of the vessel, a view of the electrodes is completely obstructed. In vacuum tubes used in repeater installations, which are under constant ob servation, the coating is quite detrimental to the observation of the tubes, since the attendant cannot observe the spacing of thevelectrodes nor detect other defects within the tubes. Furthermore, this coating prevents the free dissipation of heat in the vessel since the heat is reflected from the mirrorlike coating and remains in the vessel thereby subjecting the electrodes to excessive heat which in time will break down the thermionically active coatings on the electrodes and reduce their eiiciency.

It is an object of this invention to limit the deposit of thev getter to a relatively small portion of the glass vessel.

In accordance with this invention these reducing medium or getter iii a circular tubing having a slit on its periphery, which is supported from the electrode assembly. When the reducing medium is heated, the

vapor is emitted from the slit and deposits in a ring or halo of restricted area on the side wall of the vessel. The control of thevapor, whereby the vapor film is forced to deposit in p wall, provides a clear `view of the electrode structure from the top and sides of the ves. sel, whereby any defects in the electrodes vthemselves 'can be detected. Also the heat generated by the device is more easily dissipated through the clear wall of the vessel Isince therestricted area covered by the coating does not prevent the generate i p radiating through the glassv vessel.

' Referring to the drawings, Fig. 1 shows an electron discharge device Ywith parts disadva'ntages'are eliminated by carrying the' theformof a ring on the vessel broken away to .illustrate the invention. Fig. 2 is an enlarged sectional view of the control-line device made in accordance with this invention.

The electron dischargel device to which` this invention is particularly applicable c0n. sists of a glass enclosing vessel 10 having an inwardly projected stem 11. A cylindrical metallic base 12 is cemented to the glass vessel whereby the device Amay be inserted in a vacuum tube' socket in any well known inanner. A flattened cylindrical plate electrode f 13 is supported within the vessel by the inetallic arms 14 attached t0 a metallic collar 15 surrounding the stem 11. The insulating blocks 16 and 17 are supported at 'the' upper and -lower ends of the plate electrode by integral projections carried by the plate. Av grid electrodelS and an oxide-coated lila'- ment 19 are positioned within the plate electrode Iand supported from the insulating blocks 16 and 17.

Attached to the upper linsulating block-16,

is a metallic rod y20 passing through an aperture in the insulating block, one end of the rod 20 being passed through a parallel aperture and bcnt'at 21, at right angles to the shank of the rod 20 forming an anchor therefor. f The free end of the vrod 20 is attached to a' circularclosed ring 22, preferably by spot welding. The yring 22 isA preferably made of nickel, althoughl other metals may be used, and is formed from tubing and provided with a peripheral slit or opening 23. The' supporting rod 20 is ference of the ring so that the opening 23 -will not be obstructed at this point. A reducing medium 24, whichf'may consist of' calcium, magnesium or `any other alkaline earth metal, is inserted in the hollow tubing and thereby effectively 'supported within the glass vessel. y

The preliminary steps inthe evacuation i process consist of denuding'the electrodes of the occluded gases by bombardment or in 'any well known manner; the gases being high vacuum. Since ythe heat generated by the bombardment of the velectrodes is insufficient to vaporiae the reducing medium, it

attached to the ring 22 on the inner circumi posits on the Vessel wall.

has been found preferable to iash the reducing medium b inducing current in the ring 22 by high requenc'l alternating current supplied from a hig frequency thermionic oscillator, such as described in M. J. Kelly U. S. Patent 1,565,857, Serial No. 481,610, issued December- 15, 1925entitled: Vacuum tube manufacture, since by this method the vaporization of the medium .is accomplished inY a very sh rt period. Furthermore, the high freque cy method can be very easily controlled.

In accordance with this invention a high frequency coil, shown and described in the co-pending application mentioned` above, surrounds the glass vessel adjacent to the. portion of the vessel occupied by the reducing medium. The induced currents from the high frequency source supplies sufficient heat in the closed ring 22 to vaporize the reducing medium Within the ring whereby the vapor absorbs the residual gas and de- The vapor can only be emitted from the ring 22 through the slit 23. Therefore, 'due to the limited outlet provided .by the slit in the ring, the vapor in its travel from the ring to the glass wall will only cover alimited area shown by the (lotte tion of the spacing of the electrode can be obtained, and furthermore, that the coating does not materially lessen the radiating surface of the Vessel whereby the internal heat can be dissipated.

Although the 'invention has been shown.

and described in a particular form .it is apl portion 25. Since the vapor film. 1s restricted to a certain area in the vessel 1t 1s apparent that visual observay parent that various modifications may be made'in the structural details Without departing from the scope of the invention asl set forth in the appended claim.

What is claimed is: An electron discharge devicecomprising an evacuated vessel, an electrode assembly, a

having an openlng 1n its outer- VICTOR L. RON GI. 

